Author Ellen Szubski
On July 12, 2024, a family entered the local water park to cool down. The family consisted of a mother and her two sons. While walking toward the wave pool area, the mother stepped off the wooden stairs and onto the surrounding concrete landing. As she did so, she slipped on a puddle of water that had accumulated on the surface. She fell backward, landing on her left side and striking her elbow and the back of her head against the stairs—effectively ending the family’s outing before it began.
Painted concrete is very slippery when wet due to the paint covering the asperities or “grip” on the walking surface. The less asperities present on the walkway surface, the more slippery the floor.
An investigation revealed that landing surface appeared to be a painted smooth concrete, which was visibly wet from foot traffic and nearby splashing of the wave pool. The concrete landing surface had been painted the week before the mother’s fall. The concrete walkway area did not contain any added asperities or “grit” to increase the surface traction in that area. The process of painting the concrete with paint covered any previous or inherent asperities or “grip” on the concrete walking surface, therefore decreasing the flooring’s slip resistance. When wet, the painted concrete had an even lower slip resistance than when dry. Given the location of the wave pool in proximity to the concrete, it was likely that the area would become wet and become a slip hazard. The mother likely slipped and fell on the wet concrete due to the lack of available traction for her to remain upright. She likely would not have fallen had the painted concrete had a higher slip resistance when wet through the application of added asperities or grit.
Anti-slip coatings can be applied to walkway surfaces to increase slip resistance. These coatings increase the available traction between the walking surface and the pedestrian’s foot.
Slip and falls occur when there is an unexpected loss of traction between a person’s foot and the walking surface. Here, the pedestrian loses balance and falls. The human gait cycle consists of four phases: the stance phase, the toe-off phase, the swing phase, and the heel-strike phase. Slip and falls are most likely to occur when there is an unexpected change in the slip resistance of the walking surface during the heel-strike phase of the gait cycle. The potential for a slip and fall event increases if there is an unexpected reduction in the walkway surface’s slip resistance and the available slip resistance is too low for the pedestrian to remain upright. Some factors that contribute to slips and falls include the type of flooring and the presence of moisture or contaminants on the floor.
There are effective measures to reduce the likelihood of a slip and fall event. The best way to control slip and fall hazards is to remove the hazard completely. If slip and falls are a concern, flooring with little slip resistance should be replaced with flooring material with higher slip resistance. If replacing the existing flooring material is not possible, then guarding against or separating pedestrians from inadvertent exposure to the slippery surface is an option. Adding a non-slip coating such as grit additive increases the slip resistance of the floor and separates the pedestrian from unintentionally encountering the hazard. Lastly, hazard warnings can be used in addition to either removing or guarding a hazard to prevent slip and fall events. Property owners and management should place conspicuous signs near the hazard to warn pedestrians of the potential slip hazard.
Ellen Szubski, Ph.D., CXLT, CPSI, AHFP, is a human factors consultant at The Warren Group. She earned a Doctorate of Philosophy in Human Factors Psychology and a Master of Science in Applied Psychology from Clemson University. She did her dissertation on “The Influence of Pedestrian Biological Motion on Time-To-Collision Estimates at Night”. She is also a Certified XL Tribometrist, Certified Playground Safety Inspector and a Certified Associate Human Factors Professional (AHFP). Prior to entering the forensic field, Ellen planned and conducted experiments for a major bicycle manufacturer. She also conducted laser strike perception studies for the Department of Defense. Ellen applies her experience in Human Factors to the analysis of crash investigations and other personal injury matters. These matters often include collisions involving vulnerable road users and drivers, driver distraction, and slips, trips, and falls. She utilizes her knowledge of OSHA regulations, codes, and standards in her analysis of premises liability incidents and safety consulting. Ellen is a current member of the Human Factors and Ergonomics Society (HFES) and it’s Forensic Professional Technical Group.
